Work at elevated areas about six to twelve feet off the floor is frequently required during new construction and during repairs and maintenance. Ladders are sometimes used to reach elevated work areas, but a worker on a ladder cannot move laterally and prolonged time on a ladder is uncomfortable. For these reasons, the use of scaffolding or other type of elevated horizontal platform is greatly preferred for extended periods of such work.
A popular type of scaffolding used for residential, commercial, and industrial interior construction is commonly known as a Baker scaffold. A Baker scaffold consists of a stackable frame upon which a horizontal platform is placed at the desired height. A Baker scaffold is typically about three feet wide, six feet high, and six feet long. It typically has four wheels and is relatively lightweight to enable it to be manually pushed or carried from one location to another.
When working on a conventional Baker scaffold, the worker must climb down to the floor to move the scaffold to a different location. It would be much more convenient if the worker could move the scaffold while on it. Several different motorized attachments for a Baker scaffold have been disclosed, including those shown in Slusarenko, U.S. Pat. No. 4,053,025, issued Oct. 11, 1977; Johnson, U.S. Pat. No. 4,275,797, issued Jun. 30, 1981; and Fisher, U.S. Pat. No. 4,475,611, issued Oct. 9, 1984. These motorized attachments all suffer from the same disadvantages, they are underpowered, incapable of movement in all directions, and unstable.
Lahaie, U.S. Pat. No. 5,310,018, issued May 10, 1994, discloses a mobile scaffold with four drive wheels that is more substantial than a conventional Baker scaffold. The Lahaie mobile scaffold can move only along one axis, i.e., it cannot move in all directions. It also has a fixed length and width. Therefore, if the Lahaie mobile scaffold is made small enough to fit through small doorways and into elevators, a worker on it has little lateral movement. Conversely, if the scaffold is large enough to provide adequate lateral movement, it will not fit through small doorways or into elevators. Accordingly, a demand exists for a mobile work platform whose length is adjustable, which can travel in all directions, and which can also be used to transport heavy materials.